"For people who haven't heard about it yet or think it's too expensive, it's an ideal time to reach out and try to refinance," said Doug Leever, mortgage sales manager at Tropical Financial Credit Union in Miramar.

Leever said borrowers can expect much lower payments by getting mortgage rates below 4 percent. Some homeowners can reduce their mortgages to 15 years from 30 with only slightly higher payments than they have now.

"It's a really good opportunity," said Ryan Paton, president of Capitol Lending Group in Fort Lauderdale. "It's ridiculous the amount of savings you can get. I hope the extension will open some people's eyes."

Rising home prices have reduced the number of underwater mortgages across South Florida, but it's still a significant problem.

In the fourth quarter, 39.6 percent of mortgaged homes across Palm Beach, Broward and Miami-Dade counties were worth less than what's owed, down from 47 percent during the same period a year ago, according to real estate website Zillow.com.

Underwater borrowers can't sell their properties without bringing thousands of dollars to the closing table. Because of the lack of equity, these owners are in danger of letting the homes fall into foreclosure.

The government housing agency said it's extending HARP to help reduce losses for taxpayers and mortgage companies Fannie Mae and Freddie Mac.

"More than 2 million homeowners have refinanced through HARP, proving it a useful tool for reducing risk," FHFA Acting Director Edward J. DeMarco said in a statement. "We are extending the program so more underwater borrowers can benefit from lower interest rates."

In January, 56 percent of all refinances in Florida were through HARP, according to the latest available FHFA data.

The agency says it's planning a national campaign to educate homeowners and encourage them to take advantage of the program before it ends.

Homeowners can qualify for HARP if their mortgages were sold to Fannie or Freddie on or before May 31, 2009, and the loan-to-value ratios are greater than 80 percent.

What's more, homeowners can't have any late mortgage payments in the past six months and no more than one late payment in the past year.

Some analysts and homeowners have criticized HARP and other government housing programs because they exclude delinquent borrowers.

"It's a situation where the devil really is in the details," said Mike Larson, a housing analyst with Weiss Research in Jupiter. "When you get down to the nitty-gritty, the qualifications are a little tougher than you would expect."